This invention relates to the field of the bending machines in general, i.e. machines adapted to bend straight semifinished products having an indeterminate length and being of a constant cross-section such as pipes, rods and section bars, into plane and spatial curves, also more than a round angle, for example helically and/or spirally.
Bended pipes or section bars are largely and meaningfully used in the architectural field, both for mainly functional members, such as e.g. handrails for winding staircases and section bars for arcades, and attractive elements, such as e.g. grates, in technical systems for building, such as e.g. heating plant pipes, as well as in several industrial apparatuses such as heat exchangers.
In particular this invention concerns a bending machine comprising a frame, having a main side in which a bending head is provided including three bender rollers, whose two rollers have fixed axes of rotation, the third one having a vertically displaceable axis of rotation, as it is mounted on a slider which is movable along a vertical rectilinear guide; comprising a motor and reduction gear unit driving one or more bender rollers; comprising thrust rolls and comprising a driving cylinder of said slider.
A prior art bending machine, of the kind which this invention refers to, is perspectively shown in FIG. 1 in the accompanying drawings.
This prior art bending machine comprises a machine body, indicated by the reference numeral 1, that encloses and supports internally a motor unit of the bending machine and externally has working means. As shown in FIG. 1 (prior art), the working means comprises three grooved rollers or pulleys 2, 2', 2" which are located in a .DELTA. (delta)-shaped configuration, having one horizontal side and two oblique sides, upon a working head 1' which is provided by a main side 1a of the machine body 1. (The bending machine is shown in an usual arrangement with the working head 1' in vertical position. However the working head 1' can turn in a right angle to be displaced into a horizontal position, if desired according to working necessity.) Two rolls or thrust elements or straighteners 3, 3' are mounted approaching the two oblique sides, respectively, of delta-shaped configuration of the grooved rollers.
Arranged inside the machine body as above mentioned is a motor unit that gives the working head a torque. The motor unit comprises an electric motor that through a reduction gear rotates two toothed wheels that in turn rotate the two first rollers 2, 2'. The electric motor is located approaching the working head, i.e. the main side of the bending machine; the reduction gear, connected to the output of the motor, approaches the side of the bending machine which is opposite to the main one, or rear side. Meshed on the reduction gear are three sprockets that are driven by the motor through the reduction gear, and in turn drive the three bender rollers through respective pairs of universal joints. (In order to bend with only two instead of three rollers, the third roller can be removed from its meshing. In order to bend semifinished products with an aesthetical aim, two power-driven rollers or trailer rollers or forming rollers are required, in this case they being provided with a knurl to catch the semifinished product and thus draw it in the bending phase.)
In operation, a pipe or section bar is feed among the three grooved rollers and the trailer ones of said rollers are rotated. The thrust rolls operate to give the semifinished product being worked an axial pitch of a helicoidal spatial bending, outside the bending plane which is defined by the delta-shaped configuration of the three grooved bender rollers. The thrust rolls work by exerting a thrust force on a pipe or section bar or rod that is feed during the bending operation.
The bender roller, which is located in the apex opposite to the horizontal side of the delta-shaped configuration, the third roller--as opposed to the other two rollers, the first one and the second one--indicated by reference numeral 2", is mounted on a saddle or slider 2"a, that can be stopped in a vertically adjustable working position. As the third bender roller is displaceable along the vertical direction, its position can be adjusted in relation to the other two bender rollers, i.e. the distance between the axes of the bender rollers can be adjusted. This allows the radius of curvature to be changed in a bending operation.
A hydraulic cylinder 4 usually is provided in order to carry out linear displacements of the slider 2"a. The cylinder 4 is mounted on a shelf 4a' upon a horizontal ridge plane of the main side 1a. The cylinder 4 usually is assisted by its own drive motor (not shown). (Further, a low cost screw-type manual driving device, mounted on the same shelf 1a', can be provided instead of cylinder 4).
The bending machine is equipped with a control keyboard.
This invention starts from the following.
Both, the shelf 4a' on the main side 1a of the bending machine and the hydraulic or pneumatic or oleodynamic cylinder 4 arranged on the shelf, are limited to their specific function, i.e. to carry out the linear displacements of the slider 2"a bearing the third roller 2". In fact, the shelf plane is not available because it is occupied by the body of hydraulic cylinder; further, the positive displacements of the cylinder rod cannot be used differently for other purpose, as the cylinder rod works downward and therefore cannot cooperate with an user device.
On the contrary, it would be very advantageous that the shelf plane was available and the positive displacements of the cylinder rod, that can exert pressure as great as 12 (twelve) tons, could be utilized. In this way a tool could be installed onto the shelf and driven by the hydraulic cylinder, thus adding functions to the bending machine.
From this point of view, the same motor unit of the bending machine can be suitably utilized for the primary motion of a tool. In the prior art arrangement of the motor unit, a tool outside the bending machine cannot utilize the torque delivered by the motor unit.
On the contrary, the use of this torque would be also very advantageous, as the bending machine, with the only and the same motor-driving of principal bending means, would be able to mount and drive further tools, in particular tools able to operate on the same type of semifinished product (pipes, section bars, rods) on which the bending machine is designed to work, said further tools being driven both by a thrust (such as a thrust exerted by the above said hydraulic cylinder) and a torque (such as a torque drawn from the motor unit).
Thus, a general object of this invention is to provide a bending machine of the above mentioned type, in which the driving units can be utilized to operate tools outside the same bending machine.
In particular, an object of this invention is to provide a bending machine so that it can sustain a tool upon the shelf provided by its main side and operate said tool by utilizing the positive displacements of the rod of the hydraulic or pneumatic or oleodynamic cylinder.
Such an object is achieved according to the teaching of present invention by the following expedient.
The hydraulic driving cylinder is not installed above the shelf, rather below the shelf, suitably housed in the machine body. The shelf so cleared is provided with connection means for a tool, thus becoming a connection shelf.
A bending machine with such capacities has an advantage to be modular, i.e. it can be considered a basis unit on which a different tool can be installed from time to time. E.g. a countersink, a punching tool, a drawing die, a trimming tool etc. is able to be installed on the bending machine, all being driven by the thrust of the pre-existent hydraulic cylinder. Thus this machine, besides being a real bending machine, is also a multipurpose machine.
This advantage is important particularly in that functions strictly pertaining to pipe and section bar working can be added to bending machine so that one machine is available to carry out a number of operations on pipes and section bars. Firstly a bending machine would become also a thrust pipe bender. One really may think to install on the connection shelf a tool provided with a structure adapt to support idle counteracting rollers on the one side and on the other side with respect to a vertical axis. This vertical axis of said structure has to be coincident, when said tool is mounted on the connection shelf, with the axis of the linear displacements of the rod of the hydraulic or pneumatic cylinder. Thus, a thrust means adapt to sustain a pipe, such as e.g. a half-moon shaped grooved rest, can be connected onto the free end of the cylinder rod in order to bend a pipe against the abutment of said counteracting rollers.
A yet greater advantage would result from that a bending machine also being able to carry out functions useful to preparation for a bending operation. A pipe throughout a bending operation is considered in the following. Referring to FIG. 2 of accompanying drawings--in which it is shown schematically how e.g. a pipe is affected during a bending operation--a pipe P is feed to the space among three rollers R.sub.1, R.sub.2, R.sub.3, into the respective grooves thereof. The pipe P separates the rollers R.sub.1, R.sub.2 on the one side from the only third roller R.sub.3 on the other side with respect to a line of extension of the pipe P. The pipe P, in the bending operation, has an end cross-section of entrance P' and an end cross-section of exit P". If now one considers those generating lines that are tangent to circumference of second roller R.sub.2 and circumference of third roller R.sub.3, he can see generating lines touching the second roller in a point p' and the third roller in a point t', respectively. Then, if he considers generating lines tangent to circumference of first roller R.sub.1 and circumference of third roller R.sub.3, he can see generating lines touching the first roller in a point p" and the third roller in a point t", respectively. The pipe P is bent on the third roller only within the circumferential length defined by the points t' and t", i.e. the arc of circumference t't". From a result of this analysis, it follows that at the beginning of curving operation, when the pipe P is feeding to the bending head, its end of entrance P' reaches the tangent point p', the curving begins, but only in the length of pipe lying on the arc t't". Thus, if the pipe cross-section coincident with t', when P' is coincident with p', is indicated as T', as a result the leading length P'T' is not curved, but it remains straight. Similarly, at the finish of a curving operation, when the pipe P is exiting from the bending head, its end of entrance P" reaches the tangent point p", the curving terminates. As the curving is limited to the length of pipe lying on the arc t't", if the pipe cross-section coincident with t", when P" is coincident with p", is indicated as T", as a result the tail length P"T" remains straight. As a consequence of this, a pipe P curved according to a round angle, as shown in FIG. 2A, has a leading length P'T' and a tail length P" T", that remain straight. Thus an operator has to cut off these lengths and weld new ends so obtained, with waste of material and time.